A blog to share security, networking and cloud related technology information as @vCloudernBeer picked up on his search for his destiny in the cloud. (LinkedIn: https://www.linkedin.com/in/chowanthony)

Tuesday, November 4, 2014

OpenStack Series: Part 4 – Nova – Compute Service

Nova is the module that handles the management of virtual machine instances in the OpenStack infrastructure by being an abstraction layer that interfaces with supported hypervisors

A list of supported hypervisors for Nova can be found here. Supported hypervisor includes the KVM (libvirt/QEMU), ESXi from VMware, Hyper-V from Microsoft and XenServer. It is interested to know that Nova categorize the hypervisors into 3 groups based on the number of testing done with the drivers that interface with the hypervisor.

Group A

These drivers are fully supported. Test coverage includes:

unit tests that gate commits

functional testing that gate commits

Drivers in this group include:

libvirt (qemu/KVM on x86)

Group B

These drivers are in a bit of a middle ground. Test coverage includes:

unit tests that gate commits

functional testing providing by an external system that does not
gate commits, but advises patch authors and reviewers of results in
gerrit (the code review system).

Drivers in this group include:

Hyper-V

VMware

XenServer 6.2

Group C

These drivers have minimal testing and may or may not work at any
given time. Use them at your own risk. Test coverage includes:

(maybe) unit tests that gate commits

no public functional testing

Drivers in this group include.

baremetal

docker <- I believe due to popularity, Docker is coming back in Kilo.

Xen via libvirt

LXC via libvirt

NOTE:Drivers in Group C will be deprecated by the Icehouse release. See DeprecationPlan for details.

I think the hypervisor technology is the most matured for VMware's ESXi/vCenter Server. However, user has to pay licensing fee. On the other hand, KVM is free with Linux and is becoming more and more "enterprise ready". Of course if we compare the feature between VMware, KVM the number will favor ESXi. We have to take into consideration that not all the features are necessary for most enterprise requirement and user will have to decide which hypervisor has the best ROI (Return on Investment).

The Nova Developer Guide has a good description of the sub-components that make up of Nova services:Nova
consists of seven main components,
with the

Cloud Controller component representing the global state and
interacting with all other components.

API Server
acts as the Web services front end for the cloud controller.